It is well known that Salmonella organisms have been associated with egg products. More recently, Salmonella enteritidis (SE) has been detected within shell eggs. Presently, the presence of Salmonella within the shell egg is a major concern. Some states have enacted legislation preventing the serving of unpasteurized egg products unless fully cooked. In fact, since as early as 1969, the USDA has overseen the processing of liquid egg removed from the shell to reduce the level of Salmonella contamination to acceptable levels. However, no commercially acceptable methods have been developed to combat Salmonella in shell eggs. Since shell eggs must be used in situations where a liquid egg product cannot, it is therefore desirable to develop a commercially acceptable process for the reduction of Salmonella within shell eggs to provide a safe and functionally acceptable shell egg to the consumer.
Thermal treatments of shell egg to prevent embryonic growth in fertile eggs, to reduce incidence of spoilage during long term storage, and maintain internal quality received considerable research attention from about 1943 to about 1953. This research resulted from the nature of the egg industry at that time in that most of the eggs were produced by small flocks and the majority of the eggs used by the food industry were collected as seasonal surpluses in the spring. As a result of the production practices the eggs were more likely to lose interior quality or become unfit for human consumption because of bacterial growth or embryonic development. Research into "thermostabilization" was directed at solving these problems, which were largely perceived as embryonic growth and the contamination of the egg from contaminants external to the shell. (See Egg Science, Chapter 4, 3d Ed., 1986).
U.S. Pat. No. 2,423,233 to Funk describes the thermostabilization of shell eggs. The '233 patent described a process of heating the shell egg to arrest embryonic development in the egg. As described in the '233 patent, when heating with water the preferred times and temperatures for the heat treatment were 138 degrees Fahrenheit for from five to ten minutes. However, the work of Dr. Funk was not concerned with the elimination of pathogenic organisms. In fact, the times and temperatures suggested by Dr. Funk for heating with water would not be sufficient to cause high enough levels of Salmonella enteritidis destruction to insure that a safe shell egg would result. Furthermore, because eggs available through modern production and distribution are fresher and have a lower pH they require a different thermal process than was used by Funk.
Accordingly, it is one object of the present invention to provide a safe shell egg product which is essentially free of Salmonella and more preferably free of Salmonella enteritidis.
It is another object of the present invention to provide a commercially acceptable process for reducing the levels of Salmonella enteritidis in shell eggs to acceptable levels.
It is still a further object of the present invention to provide a method of producing a Salmonella negative shell egg without requiring additional thermal treatments which could reduce the functionality of the shell egg.